You are getting enough sleep. You are not working excessive hours. You have tried adjusting your routine, cutting back on alcohol, exercising more. And still you feel exhausted in a way that rest does not seem to fix. The tiredness is not dramatic: it is more like a persistent dimming, a sense of running at seventy percent capacity that has become your normal.
This kind of fatigue is one of the most common presentations in nutritional therapy, and it is one of the most underinvestigated. When the obvious lifestyle explanations have been ruled out, the answer is almost always in the biochemistry.
Iron and Ferritin
Iron deficiency is the most common nutritional deficiency worldwide, and fatigue is its primary symptom. The important detail is that many patients are told their iron levels are normal when what has been tested is serum iron alone. Ferritin, the protein that stores iron in the body, can be low while serum iron sits within the normal range. Low ferritin produces fatigue, brain fog, reduced exercise tolerance and hair loss, all without triggering an anaemia diagnosis.
If you have not had your ferritin specifically tested, it is worth doing so.
B Vitamins, Particularly B12 and Folate
The B vitamins are central to cellular energy production. B12 in particular is essential for the production of red blood cells and the maintenance of neurological function. Deficiency is more common than standard testing reveals, partly because the reference ranges used in routine blood tests are set to identify frank deficiency rather than functional suboptimality.
Vegans and vegetarians are at higher risk due to the animal-source exclusivity of dietary B12. Patients taking long-term proton pump inhibitors are also at increased risk, as gastric acid is required for B12 absorption.
Thyroid Function
The thyroid gland regulates metabolic rate across every cell in the body. When it is underactive, energy production slows across the board. Standard thyroid screening typically measures TSH alone. A more complete picture requires T3, T4 and thyroid antibodies, and nutritional factors including iodine, selenium and zinc play a direct role in thyroid hormone production and conversion.
Blood Sugar Dysregulation
Energy that rises and crashes through the day is often a sign of blood sugar instability rather than true fatigue. When blood glucose spikes after meals and then drops sharply, the body experiences those drops as an energy crisis. The pattern is driven by diet composition, meal timing and sometimes underlying insulin resistance, and it responds well to targeted nutritional intervention.
Adrenal Fatigue and HPA Axis Dysregulation
Sustained psychological or physiological stress places chronic demand on the hypothalamic-pituitary-adrenal (HPA) axis. Over time, this can produce a pattern of cortisol dysregulation that manifests as difficulty waking in the morning, a second wind in the evening and a persistent sense of being wired but tired. This is not a condition that shows up on a standard blood panel, but it is identifiable through functional testing and it responds to specific nutritional and lifestyle protocols.
What Clinical Nutrition Does
A clinical nutrition assessment begins with a detailed investigation of your symptoms, diet, lifestyle and health history. Where appropriate, functional testing identifies the specific imbalances driving your fatigue. The resulting protocol targets those imbalances precisely, through dietary modification, targeted supplementation and lifestyle adjustments designed around your specific picture.
When fatigue also has a nervous system component, with stress and sleep disruption playing a significant role, reiki offers a complementary pathway that supports the body in recovering from the sustained effects of HPA axis activation.
If you have been tired for longer than you can explain, book a clinical nutrition consultation with Claire Ward at Hever Health.